This invention relates to colour display apparatus and is particularly, although not exclusively, concerned with display apparatus for displaying data generated by a digital computer.
One known device for producing a colour display is a colour cathode ray tube, e.g. a shadow-mask tube having three electron guns, one for each of the three colours red, green and blue. Conventionally, separate luminance and chrominance signals are used to carry brightness and colour information for the display device these signals being transmitted simultaneously in the form of phase-modulated carrier signals. However, this involves the use of complicated and expensive decoding circuits for converting the signals into suitable form for feeding to the electron guns. For displaying data from a computer, a simpler method has been proposed, in which the computer is arranged to generate three separate colour signals, representing the red, green and blue components of the display, these signals being fed directly to the three electron guns of the tube without decoding. However, this method has the disadvantage that it requires three separate wires for connecting the computer to the display device.